Recently, with the development of electronic industries and the advance of industrial technologies, various electronic devices are designed toward small size, light weightiness and easy portability. Consequently, these electronic devices can be applied to mobile business, entertainment or leisure purposes whenever or wherever the users are. For example, various image pickup devices are widely used in many kinds of fields such as smart phones, wearable electronic devices, aerial imaging devices or any other appropriate electronic devices. Since the image pickup devices are small and portable, the users can take the image pickup devices to capture images and store the images at any time according to the users' requirements. Alternatively, the images can be uploaded to the internet through mobile networks. In other words, these electronic devices not only have important commercial values but also provide more colorful lives to people. With the improvement of the living quality, people's demands on the images are gradually increased. For example, many people are willing to acquire the images with higher quality or more imaging effects.
FIG. 1 schematically illustrates the appearance of an existing smart phone. The smart phone 9 comprises two optical lens modules 91 and 92, which are in parallel with each other. These two optical lens modules 91 and 92 can shoot the scene at different angles. After two images are captured by the two optical lens modules 91 and 92, the two images are analyzed and calculated. Consequently, a stereoscopic image with the depth-of-field data is obtained. Nowadays, the smart phone 9 with two optical lens modules 91 and 92 is produced by HTC Corporation, Sony Corporation, LG Corporation, Huawei Technologies Co. Ltd, or the like. The technologies of using two optical lens modules 91 and 92 to obtain the depth-of-field data are well known to those skilled in the art, and are not redundantly described herein.
However, the method of using the two optical lens modules 91 and 92 to shoot the same scene to acquire the depth-of-field data still has some drawbacks. For example, if two objects in the scene are arranged along the same direction as the two optical lens modules, the two objects are in parallel with respect to the smart phone 9. Under this circumstance, it is difficult to judge the depth-of-field data of the two objects, and the obtained depth-of-field data have errors. In other words, the conventional method for acquiring the depth-of-field data of the image needs to be further improved.